Electric Hybrid Drive for Retrofitting to Internal Combustion Automobiles

ABSTRACT

The subject invention is directed to a class of electric hybrid drives that can be retrofit easily to cars and trucks to reduce transportation costs. Certain embodiments include mechanisms for attachment to an existing powertrain, regenerative braking, on-the-road optimization of transportation costs depending on road and route conditions, or an operational mode in which motive power for a vehicle is solely derived from electric energy stored in a battery.

This application is entitled to the priority date of Oct. 3, 2012 forall material previously included in Provisional Application 61/709,302for Crecelius et al. The material in this provisional application isalso hereby included by reference in the instant application.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTINGCOMPACT DISK APPENDIX

Not Applicable

BACKGROUND OF THE INVENTION

The present disclosure relates generally to the technical field ofhybrid electric vehicle systems. More specifically, it relates toelectric hybrid drives for retrofitting a rotary electricmotor/generator with or without regenerative braking capability to anexisting internal combustion automotive vehicle. Still morespecifically, it relates to the mechanical interface of an electricrotary electric motor/generator to the existing driveline of an existinginternal combustion automotive vehicle.

Rising global fuel prices have improved business prospects formanufacturers of fuel-saving systems. In particular, fleet operatorsoften use their internal combustion automotive vehicles for purposes(e.g., urban delivery) which greatly reduce their average fuelefficiency. Existing vehicles waste substantial fuel when theydecelerate using friction brakes, and when operating the engine underconditions which lead to low efficiency. Existing vehicles are alsolimited to gasoline or diesel operation, which prevents operators fromchoosing the best alternative between alternate power sources forparticular driving conditions. There is thus a need for an efficient,inexpensive, and flexible electric hybrid drive which can be retrofit tointernal combustion vehicles to improve fleet operational costs.

The subject invention was developed to reduce transportation costsprimarily for fleet operators, and to do so in a manner in which initialcosts can be quickly repaid through savings. Objectives in the inventionwere to simplify installation of the electric hybrid drive onto existingvehicles, to design as simple and robust an electric hybrid drive aspossible, and to enable a vehicle equipped with the subject invention tohave a regenerative braking capacity—to slow the vehicle using themotor/generator to charge an on-board battery. The invention furtherallows optimization of engine operating conditions that increasesoverall efficiency. Also, the invention in certain embodiments allows avehicle to be propelled using solely the stored energy of its on-boardbattery.

SUMMARY OF INVENTION

The subject invention is directed to a class of electric hybrid drivesthat can be retrofit easily to cars and trucks to reduce transportationcosts. Certain embodiments include mechanisms for attachment to anexisting powertrain, regenerative braking, on-the-road optimization oftransportation costs depending on road and route conditions, or anoperational mode in which motive power for a vehicle is solely derivedfrom electric energy stored in a battery. Combinations of theseembodiments are included in the subject invention, as are embodimentswhich exclude certain of the above features.

Certain aspects of the subject invention are set forth below. It shouldbe understood that the aspects shown and discussed are not intended tolimit or exhaust the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a side view of an automotive powertrain fitted with anembodiment of the instant invention.

FIG. 2 shows a schematic view of the operational system of an embodimentof the instant invention.

FIG. 3 shows an exploded view of an implementation of the electrichybrid drive.

FIG. 4 a shows an end view of transfer shaft 301 according to animplementation of the instant invention.

FIG. 4 b shows a side view of transfer shaft 301 according to animplementation of the instant invention.

FIG. 5 shows an internal lubrication channel directing cooling fluid tothe slip yoke bearing.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows the powertrain of an automotive vehicle converted into aretrofit electric hybrid vehicle according to a particularimplementation of the present invention. An electric hybrid drive 100 isshown substituted for the extension housing of transmission 102. Slipyoke 101 engages output shaft 400 (of FIG. 4 a) of transmission 102.Motor/generator housing 103 comprises adapter element 104, housingelement 105, and motor/generator housing cover 106. Slip yoke seal 107prevents leakage of transmission fluid around slip yoke 101.

In preferred embodiments, any or all of slip yoke 101, slip yoke seal107, universal joint 108, and propeller shaft 110 can be those elementsoriginal with the automotive vehicle. They can be reused withoutmodification or with modification. However, a different embodiment cancomprise any or all of a new slip yoke, a new slip yoke seal, a newuniversal joint, and a new propeller shaft.

A cross-member mount 109 that in some embodiments will assist inanchoring motor/generator housing 103 to the existing drivetrain is alsoshown. In the embodiment shown, the electric hybrid drive and theexisting transmission output shaft automatically rotate together at thesame rotational velocity to provide power and torque to propeller shaft110.

FIG. 2 shows an electric hybrid drive schematic of a particularembodiment of the present invention 20 is an automotive vehicle in whichthe present invention has been installed. OEM elements of the originalautomotive vehicle kept in the installation comprise engine 200,automatic transmission 201, transmission control module 202, enginecontrol module 203 and front end accessory drive 204. Add-on elementsadded to the original automotive vehicle comprise rotary electricmotor/generator 210, electric power converter 211, drive controller 212,and battery pack 220.

In some embodiments of the electric hybrid drive, it will be beneficialto add an alternator onto the accessory drive of the engine, to providealternator electric power output to aid in charging battery pack 220.

Rotary electric motor/generator 210 is mounted coaxially to output shaft400 (of FIG. 4 a) of automatic transmission 201. The rotary electricmotor/generator is functionally connected to the output shaft of theautomatic transmission by means of a transfer shaft 301 (FIG. 4 a). Invarious implementations, this rotary electric motor/generator can bepowered by DC electric power or by AC electric power. In variousimplementations, rotary electric motor/generator 210 can be a permanentmagnet, induction, switched reluctance, brushed DC, wound fieldsynchronous, synchronous motor/generator, or another type ofmotor/generator with similar characteristics. In a preferred embodiment,rotary electric motor/generator 210 comprises a position feedbacksensor, which reports the position and/or rotational speed of the shaftof the rotary electric motor/generator to drive controller 212. Morepreferably, the position feedback sensor is integrated into rotaryelectric motor/generator 210.

In a preferred embodiment, rotary electric motor/generator 210 also isable to function as an electric generator. When the battery supplieselectric power to the rotary electric motor/generator, it suppliesbattery electric power output and the rotary electric motor/generatorreceives motor electric power input converted from the battery electricpower output by the electric power converter. When the rotary electricmotor/generator acts as a generator charging the battery pack, itproduces generator electric power output which is converted by theelectric power converter into charging electrical power input used tocharge the battery pack.

Particular embodiments of the operation of the electric power converterduring the process of driving the rotary electric motor/generator as amotor include: i) the electric power converter acting to convert the DCbattery electric power output into variable-frequency AC motor electricpower input; ii) the electric power converter acting to convert the DCbattery electric power output voltage into DC motor electric power inputhaving a different voltage; iii) the electric power converter acting toconvert the DC battery electric power output into pulse-width modulatedmotor electric power input; and iv) when the battery electric poweroutput and the motor electric power input have substantially the samevoltage.

In a preferred implementation, rotary electric motor/generator 210 canbe used to convert electric power from battery pack 220 into additionaltorque at the nominal rotational speed of the output shaft of theautomatic transmission, and to convert torque as supplied by engine 200and automatic transmission 201 into electrical power to charge thebattery pack. However, a system lacking the ability to charge thebattery pack from power supplied by engine 200 and automatictransmission 201 is still considered within the scope of the instantinvention.

Particular embodiments of the operation of the electric power converterduring the process of charging the battery pack comprise: i) theelectric power converter acting to convert variable-frequency ACgenerator electric power output into charging electric power input, andii) the electric power converter acting to convert DC generator electricpower output voltage into charging electric power input having adifferent voltage.

Drive controller 212 coordinates the operation of the electrical hybriddrive. The coordination comprises controlling rotary electricmotor/generator 210 to supply additional torque to the output shaft ofthe automatic transmission when desired. In a preferred embodiment,additional torque is provided during acceleration of vehicle 20.

The coordination can also comprise controlling rotary electricmotor/generator 210 to remove torque from the transmission output shaftwhen desired, thereby slowing the vehicle. In a preferred embodiment,rotary electric motor/generator 210 charges battery pack 220 at leastduring braking of vehicle 20, providing thereby the capacity ofregenerative braking. Regenerative braking can be applied with variousbraking profiles, e.g., immediate full braking, a gentle initialapplication growing to a desired level, moderate braking at all speeds,and so on. In various implementations, the instant drive comprises atleast one user control element allowing a user to control the brakingprofile of the drive.

The drive controller can also comprise at least one user control elementcontrolling a drive characteristic, e.g., fast starts using the fulltorque of the rotary electric motor/generator, gentle starts followed bygradually increasing additions of torque from the rotary electricalmotor/generator, and so on.

The drive controller comprises a communications network to communicatedata and control instructions between the various components of anelectric hybrid drive. The communications network can comprise thecontroller area network of the original automotive vehicle forcommunication of data and control instructions, a dedicated electricalhybrid drive communications network, or a combination of the two. Thecommunications network can also comprise means for providing usercommands and settings.

The drive controller comprises a digital, analog, or hybrid computerprogrammed so as to accept electric hybrid drive data and issue electrichybrid drive control instructions in such a manner to operate theelectric hybrid drive. In a particular embodiment, the drive controllersemi-automatically determines control instructions based at least on thecurrent state of the electric hybrid drive and on operator inputs. Inanother embodiment, the drive controller automatically determinescontrol instructions based at least on the current state of the electrichybrid drive and the conventional driving controls of vehicle 20.

Rechargeable battery pack 220 comprises battery modules 221 and batterymanagement system 222. Battery modules 221 comprise rechargeableelectric batteries suited to the desired performance of the electrichybrid drive. Additional considerations, such as the ratio of low-speedoperation to high-speed operation, or city center versus suburban versusrural operations, may also inform the choice of the storage capacity ofbattery modules 221.

Battery modules 221 can beneficially comprise more than one type ofbattery. For example, for some applications a combination of high-powerbatteries and high-capacity batteries may provide better systemcapabilities than modules built from only one type of battery.

Battery management system 222 provides a power conditioning interfacebetween battery modules 221 and electrical inputs to and outputs fromthose modules. For example, some batteries have extended lifespan ifcharged using pulsed current rather than continuous current. Otherscharge best if the amount of charging current is above, below, or in thevicinity of a given set point. Similarly, most batteries charge mosteffectively if the charging voltage is maintained between a minimum anda maximum charging voltage. In many cases, the rate at which energy isdrained from a battery must be limited to maintain, e.g., proper batterytemperature.

Battery management system 222 can comprise any of these functions, aswell as others that may be required to effectively use a particular typeof batteries in the battery modules. Battery management system 222 canbeneficially comprise sensors to monitor the condition (e.g., voltage,current, temperature, etc.) of the battery modules 221 and/or of theindividual batteries contained by the battery modules.

The electric hybrid drive can also comprise a line battery charger 223,thereby enabling charging of battery modules 221 from an external sourceof electricity. This converts vehicle 20 into a plug-in hybrid, with thecapability of beginning a route with fully charged battery modules. Thiscapability would be useful for improving mileage over a long-distanceroute comprising lots of highway driving, or a route that includes lotsof uphill driving early on.

The electric hybrid drive can also comprise a site power inverter 224,providing a source of AC power converted from energy stored in thebattery pack at a work site without requiring that engine 200 berunning. It is common for fleet vehicles to be driven to a work site andlargely parked during a working period. In many remote locations, havinga clean and silent source of electricity for tools is a desirablecapability which can be served by site power inverter 224.

FIG. 3 shows details of an electric hybrid drive 100 according to apreferred embodiment of the instant invention. Adapter element 104,housing element 105, and motor/generator housing element 106 ofmotor/generator housing 103 appear in an exploded view, but in the samerelationship as in FIG. 1. Rotary electric motor/generator 210 in theimplementation illustrated in FIG. 3 is a coaxial rotary electricmotor/generator having a driven rotating shaft 302 with a coaxialcylindrical aperture having splines disposed along the inner surface ofsaid aperture.

The driven rotating shaft 302 of rotary electric motor/generator 210 isfunctionally coupled to the output shaft 400 of the automatictransmission by transfer shaft 301. Shown in detail in FIG. 4, transfershaft 301 in this implementation comprises a hollow cylinder comprisinginner grooves disposed on the inside surface of the shaft so as tocouple with a set of splines on the output shaft of the automatictransmission. Transfer shaft 301 further comprises outer groovesdisposed on the external surface of the shaft so as to couple with thesplines on the hollow output shaft 302 of rotary electricmotor/generator 210. The net effect is that, when assembled, the outputshaft of the automatic transmission and the driven rotating shaft 302are locked together in rotation. In another embodiment of the instantinvention, the driven rotating shaft 302 of rotary electricmotor/generator 210 meshes properly with the transmission output shaft400 of the automatic transmission so that no transfer shaft is required.It will be clear to one skilled in the art that the means fortransferring torque can include a coaxial speed matcher, such as a setof planetary gears. A variety of direct-drive couplings are also wellsuited for transferring torque between the driven rotating shaft and thetransmission output shaft

In a particular embodiment, rotary electric motor/generator 210 requiresliquid cooling. For this purpose cooling fluid fittings 303 circulateautomatic transmission fluid through the rotary electricmotor/generator. The level of the cooling fluid can be monitoredvisually through cooling fluid viewport 307. Coolant access port 304provides access to the motor/generator coolant.

In a preferred embodiment, the original slip yoke 101 of the automotivevehicle 20 is used in the retrofit electric hybrid vehicle. The originalbearing supporting the slip yoke, however, is typically removed alongwith the extension housing of the transmission 102. The original bearingsupporting the slip yoke is replaced by slip yoke bearing 305, which isthen sealed around the original slip yoke by slip yoke seal 306.

FIGS. 4 a and 4 b show details of transfer shaft 301. The transfer shaft301 rotationally couples hollow output shaft 302 of rotary electricmotor/generator 210 to output shaft 400 of the automatic transmission sothat all three elements rotate together. In a particular embodiment,this is accomplished by providing transfer shaft 301 with internalsplines 401 and external splines 402 that mesh, respectively, withtransmission output shaft splines 403 and rotating shaft splines 404.The shape of the internal splines 401 and the external splines 402 arechosen to function properly within a particular embodiment of theinstant invention.

Lubrication for the slip yoke bearing 305 is originally provided fromthe internal structure of the automatic transmission 102 by any of anumber of designs, e.g., a splash-lube system. In some embodiments ofthe instant invention, this source of lubrication may be blocked byrotary electric motor/generator 210 and its housing. In a particularembodiment of the instant invention, the automatic transmission fluidused for cooling rotary electric motor/generator 210 is also directed toslip yoke bearing 305 for purposes of lubrication. In a furtherembodiment as illustrated in FIG. 5, the automatic transmission fluid isrouted from the cooling fluid fittings 303 through an internallubrication channel 501 within housing element 105 and motor/generatorhousing cover 106 to slip yoke bearing 305.

While the foregoing written description of the invention enables one ofordinary skill to make and use what is considered to be the best modethereof, those of ordinary skill will also understand and appreciate theexistence of variations, combinations, and equivalents of the specificembodiment, method, and examples herein. The invention is therefore notintended to be limited by the above described embodiments, methods, andexamples, but by all embodiments and methods within the scope and spiritof the invention as claimed below.

1. An electric hybrid drive for retrofitting to internal combustionautomobiles that include an internal combustion engine, a transmissionwith a transmission case and a transmission output shaft, comprising: a)a rotary electric motor/generator comprising a driven rotating shaftpierced coaxially along the axis of rotation of the driven rotatingshaft, said pierced shaft having a sufficiently large aperture for thetransmission output shaft to pass through, and at least one of a rotaryposition sensor or a tachometric sensor; b) means for mounting themotor/generator so that the driven rotating shaft is coaxial with thetransmission output shaft, and so that the motor/generator issubstantially fixed with respect to the transmission case; c) means fortransferring torque between the driven rotating shaft and thetransmission output shaft; d) a slip yoke bearing; e) a rechargeablebattery pack comprising means to provide battery electric power output,and further comprising means to accept charging electric power input; f)an electric power converter functionally connected to the rechargeablebattery pack and the motor/generator, comprising motor driving circuitrythat converts battery electric power output from the rechargeablebattery pack into motor electric power input for the rotary electricmotor/generator; g) additional sensors that produce sensor datadescribing the current operating condition of the drive; and, h) a drivecontroller that acquires all sensor data and from that generates andsends control signals to the other components of the electric hybriddrive.
 2. The drive of claim 1, wherein the electric power converterfurther comprises battery charging circuitry that converts generatedelectric power output from the motor/generator into charging electricpower input for the rechargeable battery pack.
 3. The drive of claim 1,wherein the means for transferring torque between the driven rotatingshaft and the transmission output shaft comprises a set of planetarygears.
 4. The drive of claim 1, wherein the means for transferringtorque between the driven rotating shaft and the transmission outputshaft comprises a direct-drive coupling.
 5. The drive of claim 1,wherein the aperture of the driven rotating shaft defines an innercylindrical surface thereon.
 6. The drive of claim 5 in the case whenthe transmission output shaft is a splined transmission output shaft,wherein the inner cylindrical surface of the driven rotating shaftfurther comprises internal splines disposed thereon so that the internalsplines mesh with the splines on the transmission output shaft.
 7. Thedrive of claim 1, wherein the means for transferring torque between thedriven rotating shaft and the transmission output shaft comprise atransfer shaft that substantially prevents relative rotation of thedriven rotating shaft and the transmission output shaft.
 8. The drive ofclaim 5, wherein the transfer shaft comprises a cylindrical transfertube having external splines which mesh with the internal splinesdisposed on the driven rotating shaft.
 9. The drive of claim 8 in thecase when the transmission output shaft is a splined transmission outputshaft, wherein the cylindrical transfer tube further comprises internalsplines which mesh with the splines on the transmission output shaft.10. The drive of claim 1, further comprising a cooling system comprisinga cooling fluid, wherein the purpose of said system includes the coolingof the rotary electric motor/generator.
 11. The drive of claim 10,wherein the cooling fluid comprises at least one fluid selected from thegroup consisting of water, ethylene glycol, oil, and automatictransmission fluid.
 12. The drive of claim 10, wherein the coolingsystem further includes means to lubricate the slip yoke bearing withthe cooling fluid.
 13. The drive of claim 1, wherein the means formounting the motor/generator comprises a motor/generator housingattached to the transmission case.
 14. The drive of claim 13, whereinthe motor/generator housing comprises an adapter element bolted onto thetransmission case.
 15. The drive of claim 1, wherein the means formounting the motor/generator comprises a cross-member mount functionallyattached to the motor/generator housing.
 16. The drive of claim 10,wherein the means for mounting the motor/generator comprises amotor/generator housing attached to the transmission case.
 17. The driveof claim 16, wherein said motor/generator housing comprises said meansto lubricate the slip yoke bearing with the cooling fluid.
 18. The driveof claim 17, wherein said means to lubricate comprises a buriedlubrication channel within the motor/generator housing.
 19. The drive ofclaim 1, wherein the rotary electric motor/generator is a direct currentmotor.
 20. The drive of claim 1, wherein the rotary electricmotor/generator is an alternating current motor.
 21. The drive of claim1, wherein the rotary electric motor/generator is selected from thegroup consisting of permanent magnet motors, induction motors, switchedreluctance motors, brushed direct current motors, wound fieldsynchronous motors, and synchronous reluctance motors.
 22. The drive ofclaim 1, wherein the rechargeable battery pack comprises rechargeablebatteries.
 23. The drive of claim 22, wherein the rechargeable batteriesare collected into at least one battery module.
 24. The drive of claim1, wherein the rechargeable battery pack further comprises a batterymanagement system.
 25. The drive of claim 24, wherein the batterymanagement system comprises a power conditioning interface.
 26. Thedrive of claim 1, further comprising a line battery charger generatingcharging electrical power input from an external electrical source. 27.The drive of claim 1, further comprising a site power inverter thatconverts battery electric power output into mains power.
 28. The driveof claim 1, wherein the sensors include at least one sensor chosen fromthe group consisting of voltage sensors, current sensors, temperaturesensors, fuel rate sensors, automobile speed sensors, and operator inputsensors.
 29. The drive of claim 2, wherein the electric power converterfurther comprises a regenerative braking mode.
 30. The drive of claim29, wherein the drive controller comprises at least one user controlelement allowing a user of the drive to control the braking profile ofregenerative braking of the retrofitted internal combustion automobile.31. The drive of claim 1, wherein the drive controller comprises atleast one user control element allowing a user of the drive to controlthe relative proportions of torque transferred to the transmissionoutput shaft from the rotary electric motor/generator and from theinternal combustion engine.
 32. The drive of claim 1 in the case wherethe transmission is an automatic transmission.
 33. The drive of claim 1in the case where the transmission is a manual transmission.
 34. Anelectric hybrid drive for retrofitting to a motor-powered conveyance,said conveyance comprising a motor output shaft, the claimed inventionfurther comprising: a) a rotary electric motor/generator comprising adriven rotating shaft pierced coaxially along the axis of rotation ofthe driven rotating shaft, said pierced shaft having a sufficientlylarge aperture for the motor output shaft to pass through, and at leastone of a rotary position sensor or a tachometric sensor; b) means formounting the motor/generator so that the driven rotating shaft iscoaxial with the motor output shaft; c) means for transferring torquebetween the driven rotating shaft and the motor output shaft; d) arechargeable battery pack comprising means to provide battery electricpower output, and further comprising means to accept charging electricpower input; e) an electric power converter functionally connected tothe rechargeable battery pack and the motor/generator, comprising motordriving circuitry that converts battery electric power output from therechargeable battery pack into motor electric power input for the rotaryelectric motor/generator; f) additional sensors that produce sensor datadescribing the current operating condition of the drive; and, g) a drivecontroller that acquires all sensor data and from that generates andsends control signals to the other components of the electric hybriddrive.